Atypical rat cerebellar immunoreactivity in a patient with familial amyloid polyneuropathy

Abstract

Objective: To describe an atypical immunoreactivity against Purkinje cells and glia of rat cerebellum in a case of transthyretin (TTR)‐related familial amyloid polyneuropathy (FAP). Background: TTR‐FAP is an autosomal dominant disease, usually presenting as a progressive sensory or sensorimotor polyneuropathy with autonomic disturbances. Case report: A 68‐year‐old man complained of a two‐year history of severe orthostatic hypotension, diarrhea and progressive sensorimotor polyneuropathy. The neurological examination showed a severe distal weakness at the four limbs, areflexia and distal impairment of pin‐prick sensation and proprioception. The patient was bed‐ridden because of the severe hypotension. Routine laboratory studies, autoantibodies, neoplastic markers and immunoelectrophoresis were negative; thyroid function was impaired with reduced levels of TSH, T3 and high level of anti‐tireoglobulin antibodies. An unusual reactivity against Purkinje cell membrane and glial cells of rat cerebellum white matter was found on immunohistochemistry. Western blot for the detection of onconeural antibodies (Hu, Ri, Yo and Amphiphysin) was negative. Electrophysiological studies showed a severe axonal sensorimotor polyneuropathy. Chest x‐ray and chest and abdomen CT scans did not reveal any malignancies. Genetic analysis revealed a Phe 64 Leu mutation on TTR gene. Discussion: The unusual immunoreactivity found in our patient has not been previously described. Our case report may be a warning to clinicians to suspect a genetic origin in patients with polyneuropathy and atypical pattern of neuronal immunoreactivity.